#pragma once
#include <string.h>
#include <assert.h>
#include <iostream>
namespace myvector
{
	template <class T>
	class vector
	{
	public:
		typedef T* iterator;
		typedef const T* const_iterator;

		iterator begin()
		{
			return _start;
		}

		iterator end()
		{
			return _finish;
		}

		const_iterator begin() const 
		{
			return _start;
		}

		const_iterator end() const
		{
			return _finish;
		}

		vector()
			:_start(nullptr)
			, _finish(nullptr)
			, _end_of_storage(nullptr)
		{}

		vector(const vector<T>& v)
		{
			_start = new T[v.capacity()];
			memcpy(_start, v._start, sizeof(T)*v.size());
			/*for (size_t i = 0; i < v.size(); i++)
			{
				_start[i] = v._start[i];
			}*/

			_finish = _start + v.size();
			_end_of_storage = _start + v.capacity();
		}


		~vector()
		{
			if (_start)
			{
				delete[] _start;
				_start = _finish = _end_of_storage = nullptr;
			}
		}

		void swap(vector<T> v)
		{
			std::swap(_start, v._start);
			std::swap(_finish, v._finish);
			std::swap(_end_of_storage, v._end_of_storage);
		}

		vector<T> operator=(vector<T> v)
		{
			swap(v);
			return *this;
		}

		T& operator[](size_t pos)
		{
			assert(pos < size());
			return _start[pos];
		}

		const T& operator[](size_t pos) const
		{
			assert(pos < size());
			return _start[pos];
		}

		void resize(size_t n, const T& val = T())//用匿名对象给缺省值
		{
			if (n < size())
			{
				_finish = _start + n;
			}
			else
			{
				reserve(n);

				while (_start + n != _finish)
				{
					* _finish = val;
					++_finish;
				}
			}
		}

		void reserve(size_t n)
		{
			if (n > capacity())
			{
				size_t sz = size();
				T* tmp = new T[n];
				if (_start)
				{
					memcpy(tmp, _start, sizeof(T) * sz);
					/*for (size_t i = 0; i < size(); ++i)
					{
						tmp[i] = _start[i];
					}
					delete[] _start;*/
				}
				_start = tmp;
				_finish = _start + sz;
				_end_of_storage = _start + n;
			}
		}

		void push_back(const T& x)//尽量传引用
		{
			if (_finish == _end_of_storage)
			{
				size_t newcapacity = capacity() == 0 ? 4 : capacity() * 2;
				reserve(newcapacity);
			}
			*_finish = x;
			++_finish;
		}

		iterator insert(iterator pos, const T& x)
		{
			assert(pos >= _start && pos <= _finish);

			if (_finish == _end_of_storage)
			{
				size_t len = pos - _start;

				size_t newcapacity = capacity() == 0 ? 4 : capacity() * 2;
				reserve(newcapacity);
				pos = _start + len;
			}
			iterator end = _finish - 1;
			while (end >= pos)
			{
				*(pos + 1) = *end;
				--end;
			}
			*pos = x;
			++_finish;
			
			return pos;
		}

		iterator erase(iterator pos)
		{
			assert(pos >= _start && pos < _finish);

			iterator it = pos + 1;
			while (it != _finish)
			{
				*(it - 1) = *it;
				++it;
			}

			--_finish;

			return pos;
		}

		size_t capacity() const
		{
			return _end_of_storage - _start;
		}

		size_t size() const
		{
			return _finish - _start;
		}

	private:
		iterator _start;
		iterator _finish;
		iterator _end_of_storage;
	};
}